1. Field of the Invention
This invention relates to a printing device for printing a still picture, such as a picture formed by a video camera or a still television picture, using a vaporized dye, and a photographic paper on which printing is made by such printing device.
2. Description of the Related Art
There has hitherto been known a printing device, such as a sublimation printer, in which a sublimation ink ribbon, coated with a sublimable dye, is superposed on the photographic paper, and an electric energy corresponding to the picture information is applied to a thermal head for subliming the dye on the ink ribbon under a heat energy supplied from the thermal head for transcribing the sublimed dye onto the photographic paper.
The sublimation ink ribbon is prepared by dissolving a sublimable dye in e.g. a solution of acetate or polyester and adding a dispersant to the resulting solution to form a colloidal solution in the form of an ink which is mixed with a binder and subsequently coated on a base paper.
The photographic paper usually has a receptor layer of a heat transfer recording material on a photographic base paper. Among the heat transcription recording materials in current use is a dye-like resin, such as polyester or polycarbonate resin, admixed with a lubricant.
The thermal head is a device which translates an electrical energy into a heat energy, that is a device in which the dye is sublimed from the sublimation ink ribbon under the Joule""s heat generated on flowing the current through a resistor for transcribing the sublimed dye onto the photographic paper.
When the recording picture is formed on the photographic paper by the above-mentioned sublimation ink ribbon and thermal head, the receptor layer of the photographic paper undergoes the following changes:
That is, when the heat energy is applied from the thermal head, the polyester resin, for example, of the receptor layer undergoes glass transition and softening and thereby turned into the liquid, at the same time that the dye in the sublimation ink ribbon is transferred onto the receptor layer so as to be dissolved or dispersed in the layer to form the recording picture.
With the above-described sublimation printer, in which printing is made on the photographic paper using the sublimation ink ribbon and the thermal head, it is necessary to provide an ink ribbon takeup mechanism for rewinding the ink ribbon and a heat radiating mechanism for the thermal head. On the other hand, the thermal head usually has a heat conversion efficiency of not higher than 10%, thus leading to considerable power consumption. Thus it has been difficult with the conventional sublimation type printer to realize saving in power and reduction in size and costs.
On the other hand, the sublimation ink ribbon can be used only once for each picture and hence is not economically desirable. Besides, the used-up ink ribbon cassette can not be regenerated and hence is to be discarded in a manner of not destroying the earth""s environment.
Besides, the printing by such printing device is carried out by stacking dyes of yellow (Y), magenta (M).and cyan (C), so that it becomes necessary to perform three cycles of the complicated and time-consuming operations of feeding the ink ribbon, vertically moving the thermal head and feeding the photographic paper.
The thermal head generally has the line-head structure of thin resistors generated by sputtering being arranged in a line, thus the size of the printing paper cannot be set freely.
Since it is generally desirable to heat the receptor layer on the photographic paper when subliming and transcribing the sublimable dye onto the photographic paper by the thermal head, it has been a conventional practice to increase the thrusting force of the thermal head to raise the tightness of contact between the ink ribbon and the photographic paper and to apply heat to the receptor layer of the photographic paper by the thermal head. It should be noted that, if the force of thrusting the thermal head to the ink ribbon and the photographic paper is increased, the driving force necessary for the movement of the thermal head, rewinding of the ink ribbon and the feed of the photographic paper has to be correspondingly increased. In addition, since the ink ribbon is prepared by coating the dye processed into an ink on the base paper, as described above, the heat reaches the receptor layer via the base paper and the dye layer. Besides, since air layers tend to be produced between the respective layers, the heat to be applied to the receptor layer needs to be set to take account of heat losses produced in each layer, thus lowering the heat efficiency.
On the other hand, the produced picture tends to be lowered in quality if the photographic paper is not whitened at least directly after printing.
In view of the above-described status of the art, it is an object of the present invention to provide a printing device in which saving in power and reduction in size and costs may be realized without employing a thermal head or an ink ribbon. It is another object of the present invention to provide a printing device in which the printing time may be shortened and the printing paper size may be set freely to assure high picture quality of the printed picture.
It is a further object of the present invention to provide a photographic paper a receptor layer of which may be heated efficiently by the printing device to assure high picture quality of the printed picture.
According to the present invention, there is provided a printing device for thermal transcription of a vaporizable dye onto a photographic paper comprising a dye tank for containing a vaporizable dye, an entrance section for liquefying the vaporizable dye contained in the dye tank and transporting the vaporized dye, and a vaporizing section for vaporizing the liquified dye transported by the entrance section, wherein the dye vaporized by the vaporizing section is thermally transcribed onto the photographic paper.
Preferably, the vaporizable dye contained in the dye tank is powdered.
Preferably, the vaporizing section vaporizes the liquefied dye transported by the entrance section by the heat of vaporization generated responsive to a laser light.
Preferably, the laser light employed for generating the heat of vaporization in the vaporizing section is a laser light having equalized radiation intensity distribution.
Preferably, a region from the dye tank to the vaporizing section is maintained at a temperature of 50xc2x0 C. to 300xc2x0 C.
Preferably, the entrance section transports the liquefied dye to the vaporizing section by taking advantage of the capillary phenomenon.
Also preferably, the vaporizing section causes the vaporized dye to be deposited on the photographic paper by taking advantage of a diffusion phenomenon with the aid of beads.
According to the present invention, there is also provided a printing device for thermal transcription of a vaporizable dye onto a photographic paper comprising a containing section for containing a vaporizable dye, a supplying section for supplying the vaporizable dye supplied from the containing section, and a vaporizing section for vaporizing the vaporizable dye supplied by the supplying section under the heat of vaporization, wherein the vaporizable dye vaporized by the vaporizing section is thermally transcribed onto the photographic paper.
Preferably, the vaporizable dye contained in the containing section is a particulate vaporizable dye and the vaporizable dye supplied by the supplying section to the vaporizing section is also a particulate vaporizable dye.
Preferably, the vaporizable dye contained in the containing section is the vaporizable dye deposited on spherical-shaped bodies and the vaporizable dye supplied by the supplying section is also a vaporizable dye deposited on spherical-shaped bodies.
Preferably, the supplying section puts any excess amount of the vaporizable dye to circulation.
The supplying section may put any excess amount of the vaporizable dye to circulation with the aid of beads.
Preferably, the supplying section adds heat responsive to the laser light to the vaporizable dye as the heat of vaporization.
Preferably, the laser light employed for generating the heat of vaporization in the vaporizing section is a laser light having equalized radiation intensity distribution.
According to the present invention, there is also provided a photographic paper in which a vaporized vaporizable dye is absorbed on a receptor layer provided as an upper layer of the photographic paper base, wherein a light absorbing layer formed by a light absorbing agent is provided between the photographic paper base and the receptor layer.
Preferably, the light absorbing layer is whitened in color by thermal destruction of the light absorbing agent itself by a light radiating body in a printing device.
Preferably, the light absorbing layer is whitened in color by thermal destruction of a capsule enclosing a whitening agent therein by a light radiating body in a printing device, wherein the capsule is mixed into the light absorbing layer.
As the light absorbing agent, an infrared ray absorber capable of absorbing infrared rays may be employed. Some of the infrared ray absorbers exhibit color extinguishing characteristics.
Typical of the light absorbing agent is a functional near-IR absorption coloring matter manufactured by SHOWA DENKO KK under the trade name of IR 820B which exhibits maximum absorption for the light having a wavelength of 825 nm. If it is allowed to exist along with an ammonium salt of organic boron, such as tetrabutyl ammoniumbutyl triphenyl borate, in a solution, it absorbs the near IR rays, so that its color is extinguished.
Examples of the whitening agents include titanium oxide, zinc oxide and calcium oxide.
The capsules employed for enclosure of the whitening agents may be formed of condensates, such as polyurea or polyurethane, homopolymers such as polyethylene or polyvinyl alcohol or waxes such as paraffins or lipids.
According to the present invention, there is also provided a printing device in which a vaporizable dye is thermally transcribed onto a receptor layer provided as an upper layer of the photographic paper base, comprising a light radiating body for whitening the color of a light absorbing agent of a light absorbing layer provided between the photographic paper base and the receptor layer.
Preferably, the light emitting body radiates a laser light.
Meanwhile, the term xe2x80x9cvaporizable dyexe2x80x9d used in the present invention means collectively a solidified disperse dye, a liquefied disperse dye, a vaporized disperse dye, a sublimable dye and a disperse dye. Thus the vaporizable dye is defined as a dye having a temperature domain, in a temperature range of from 25xc2x0 C. up to a decomposition temperature, for which temperature domain the vapor pressure is not less than 0.01 Pascal, on the provision that, if the dye molecules are associated in a gaseous phase at an average association number of n, the vapor pressure divided by the average number of association n is not less than 0.01 Pascal.
Although a sublimable dye changed from its solid state to a gaseous state may be contemplated as the vaporizable dye, a dye having the state of a liquid between a solid state and a gaseous state is also included within the meaning of the vaporizable dye.
Among a variety of the vaporizable dyes, a yellow dye, having a color index number xe2x80x9cC. I. Disperse yellow 201xe2x80x9d, manufactured by SUMITOMO KAGAKU KK under the trade name of xe2x80x9cESC-Yellow 155xe2x80x9d and a cyan dye having a color index number xe2x80x9cC. I. Solvent Blue 63xe2x80x9d, manufactured by SUMITOMO KAGAKU KK under the trade name of xe2x80x9cESC-Blue 655xe2x80x9d are employed in the printing device of the present invention. As a magenta dye, a tricyanomethine dye manufactured by MITSUBISHI KASEI KK under the trade name of xe2x80x9cHSR-2031xe2x80x9d is employed.
With the printing device according to the present invention, the dye tank stows the particulate vaporizable dye, and the entrance section liquefies the vaporizable dye and transports the thus liquefied dye to a vaporizing section, which vaporizes the liquefied dye transported by the entrance section under the heat of vaporization supplied by the laser light for transcription of the vaporized dye onto the photographic paper. The heat generating effect of the vaporizing section is improved by the laser light to enable the size of the heat radiating mechanism to be reduced. Printing becomes possible without employing an ink ribbon or a thermal head, as a result of which power saving and reduction in size and costs may be achieved. By preliminary heating within a low heat conducting material and employing the heat corresponding to the intensity of the laser light for vaporization, the heat efficiency may be improved. The degree of freedom in photographic paper size may be increased because no ink ribbon is necessitated. By providing a light absorbing layer in the photographic paper, the operating efficiency is improved. Besides, the printing time may be shortened.
It is also possible to conduct the liquefied vaporizable Y-dye to the vaporizing section by taking advantage of the capillary phenomenon with the aid of beads, or to use beads in the vaporizing section.
Since the receptor layer of the photographic paper may be heated by the laser light, the portions of the photographic paper other than the receptor layer are not affected by heat.
If the laser light has a flat light intensity distribution, the photo-thermal conversion efficiency may be improved.
With the sublimation type printing device according to the present invention, the containing section stows the particulate vaporizable dye, and the entrance section liquefies the particulate vaporizable dye and transports the thus liquefied dye to a vaporizing section, which vaporizes the liquefied dye transported by the entrance section under the heat of vaporization corresponding to the laser light intensity for transcription of the vaporized dye onto the photographic paper. In this manner, printing becomes possible without employing an ink ribbon or a thermal head so that the printing device may be reduced in size and weight. Dye exchange may be facilitated because the containing section stowing the dye therein may be dismounted and exchanged for new ones. Since the heat of vaporization corresponds to the laser light, excess heat or heat radiation is not required to enable the energy saving. Since the dye may be supplied singly, the photographic paper needs to be fed only once so that the printing time may be shortened. Free-size printing becomes possible because there is no limitation as to the photographic paper size imposed by the ink ribbon.
Besides, since the light absorbing layer formed of a light absorbing agent capable of generating heat by efficiently absorbing the light is provided between the receptor layer and the photographic paper base, the receptor layer may be heated directly to assure a high quality of the printed picture.
In addition, since a light radiating body interposed between the receptor layer and the photographic paper base of the photographic paper whitens the color of the light absorbing agent of the light absorbing layer to assure the high quality of the printed picture.
Consequently, if printing is made on the above-mentioned photographic paper by the above-mentioned printing device, the printing efficiency may be improved and the thrusting force between the dye and the receptor layer may be reduced, while resistance to abrasion may be improved. The picture quality may be improved because the light absorbing agent may be whitened in color.
If the laser light radiated by a laser block as the above-mentioned light radiating body may be of equalized light intensity distribution, it becomes possible to equalize the heat conversion occurring at the light absorbing layer of the photographic paper.
The above and other objects and advantages of the present invention will become apparent from the following description of the preferred embodiments and the claims.